a phase 3 study to evaluate the efficacy and safety of efgartigimod iv in patients with acetylcholine receptor binding antibody seronegative generalized myasthenia gravis

Conditions: Generalized Myasthenia Gravis

Summary: the primary purpose of this study is to measure the efficacy and safety of efgartigimod iv compared to placebo in participants with acetylcholine receptor binding antibody (achr-ab) seronegative generalized myasthenia gravis (gmg). the study consists of a part a where participants will be randomized to receive either efgartigimod iv or placebo iv and a part b where participants completing part a will receive open-label efgartigimod iv. participants will be in the study for up to (approximately) 2.5 years.


Eligibility criteria:
inclusion criteria: * the participant is at least 18 years of age and the local legal age of consent for clinical studies when signing the icf. * the participant is capable of providing signed informed consent and following with protocol requirements. * the participant agrees to use contraceptive measures consistent with local regulations and the women of child-bearing potential (wocbp) must have a negative serum pregnancy test result at screening and a negative urine pregnancy test result at baseline before receiving the study drug. * the participant has no known weakness in infancy and later develop fatigable weakness after aged 16 years and diagnosed with acquired gmg of both of the following: 1. history of abnormal neuromuscular transmission demonstrated by single fiber electromyography or repetitive nerve stimulation (rns) or is anti-muscle-specific kinase antibodies (musk-ab) seropositive 2. either a history of positive edrophonium chloride test or a demonstrated improvement in mg signs with treatments such as oral acetylcholinesterase (ache) inhibitors, plasma exchange (plex), immunoabsorption, or intravenous immunoglobulin (ivig)/ subcutaneous immunoglobulin (scig) treatment * the participant is receiving a stable dose of mg therapy before screening that includes acetylcholinesterase (ache) inhibitors, steroids, or nonsteroidal immunosuppressive therapies (nsists) in combination or alone. exclusion criteria: * known autoimmune disease or any medical condition that would interfere with an accurate assessment of clinical symptoms of gmg or puts the participant at undue risk * history of malignancy, cancer, unless considered cured by adequate treatment with no evidence of recurrence for ≥3 years. adequately treated participants with the following cancers can be included at any time: basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, carcinoma in situ of the breast, incidental histological findings of prostate cancer * clinically significant active infection that is not sufficiently resolved in the investigator's opinion or positive serum test at screening for active infection with any of the following: hepatitis b virus (hbv), hepatitis c virus (hcv), hiv * history of or current alcohol, drug, or medication abuse as assessed by the investigator * pregnant or lactating state or intention to become pregnant during the study * live or live-attenuated vaccine received \&lt;4 weeks before screening * worsening muscle weakness secondary to concurrent infections or medications * received a thymectomy less than 3 months before screening or thymectomy is planned during the study the complete list of exclusion criteria can be found in the protocol.